As with any car that gets produced, there is usually a chassis number assigned to the car for historical reasons. In the case of custom cars, the owner assigns what ever number he wants to put into the frame.
In the case of the Alfa Romeo Veloce’s, as I have come to understand, is that the car was built as a 750 Normale or Veloce chassis depending upon the chassis changes, and a “F” stamped into the chassis somewhere between the 1495 and the following serial numbers. This stamp is what gives it the Veloce designation, however there is one caveat to all of this. There are “some” Veloce’s that didn’t get the “F” stamp. Just recently there have been two that I have seen photographic evidence that they didn’t have this stamping. So,where does that leave the question of Veloce/not a Veloce. That falls to Marco at the Alfa Romeo archives to sort out from the data bank that was put together by Elivra Ruocco when she was in charge of Alfa Romeo documents. She retired from Alfa Romeo after having worked for Cav. Sr. Luigi Fusi, famous Alfa Romeo author as his secretary and having been put in charge of inputting all of the Alfa Romeo chassis numbers from the hand written books.
However, when we look into the chassis numbers a little closer, you will note that there are 3 numbers stamped into some of the Alfa’s. Most likely there are two, but in the case of the Giulia Spider Veloce it has 3 numbers. Sprint Veloce’s and Sprint Speciales’ have 2 numbers.
If you have a Normale that has been “Veloce-ized” it will still have the Normale chassis designation in the factory books. An “abnormale” as we call it has had the Solex replaced with the Weber carbs and high performance cams to bring it in line with more horsepower like the Veloce.
Lets take these numbers and see where they take us. This discussion came about from the Alfa Bulletin Board and the “hidden number”. The Spider Veloce was built by PininFarina. They had their own numbering system and it depended upon which car went down the assembly line in order. That number was how PF kept parts straight in house. So some PF cars could be in line with Alfa Romeo chassis. This “hidden number” is stamped in the floor of the trunk. If your trunk floor has been replaced, there isn’t any way to know what your PF number was, as there isn’t any documentation that I know of to show what chassis number got what number. If someone has a source, it would prove to be very interesting to see what cars went down the assembly line.
Your PF number in the trunk is located directly below the trunk lock center support. It will be a 5 or 6 digit number. My Giulia Spider Veloce 390681 has a “107xxx” PF number.
This is the Pininfarina number stamped into the floor of a Spider
Also, on the Giulia Spider Veloce there is a 3rd number that is stamped into the chassis. Along the drip rail that surrounds the trunk is stamped 10118. This is a tipo/type designator that identifies the chassis as being a Giulia Spider Veloce. Do other Alfa 750-101 Spiders have this number? Not that I know, but I am always open to other information.
Now take the Sprint Speciale and the Sprint Veloce are both a Bertone chassis. They had their own in-house numbering system and it was different than PF. This number is stamped into the “chassis” usually on the passenger side of the engine compartment just above the chassis number. It is usually a *XXXXX*
Bertone Chassis number on a Sprint Speciale
- Bertone number for a Sprint Veloce on cowling
arrangement. The hidden number in the Sprint Speciale is the last 3 digits of the Bertone number are stamped into the bumpers and corresponding trim pieces. The Sprint Speciale and Sprint were custom built, so swapping body parts may not always fit directly but require some custom body adjustments for proper fitment. So if you are taking apart your Sprint or Sprint Speciale, don’t lose parts! If you find that your parts have different numbers stamped on them, most likely they came from another donor car. In some cars, behind the door or interior parts, the factory sometimes hand wrote in chalk or grease pencil the chassis or Bertone number.
Veloce Register 
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Can the “Hidden number” plus the chassis number plus the number stamped on the bell house be decoded to arrive at the VIN number?
To answer your question…no. the engine number is stamped on the back part of the engine block and not on the transmission. The only thing you can arrive at from the engine number is what model car it came from and year. It can not be connected to a specific car unless you can convince Alfa Romeo to give you that information. So far, no one has been able to do that.